US agencies warn Iran-linked actors are targeting internet-exposed water and energy control systems, risking disruption.
Federal agencies updated their cybersecurity advisory this week: Iran-linked actors are inside American water and energy control systems, and they’re not just looking around. They’re changing things.
The updated advisory from CISA, the FBI, NSA, and the Department of Energy says these actors are getting into programmable logic controllers, the small industrial computers that run pumps, valves, and safety alarms. Once inside, they can mess with what operators see on their screens. That’s how you get outages nobody saw coming.
“The authoring agencies urgently warn U.S. organizations of ongoing Iranian-affiliated cyber targeting of internet-connected operational technology (OT) devices, including programmable logic controllers (PLCs).” reads the advisory. “These actions disrupted PLCs across several U.S. critical infrastructure sectors through malicious project file interactions and manipulation of data on human machine interface (HMI) and supervisory control and data acquisition (SCADA) displays, resulting in operational disruption and financial loss.”
This isn’t new territory. Back in April, the same agencies flagged Iranian hackers going after Rockwell Automation controllers specifically. The updated advisory widens the net. Now Schneider Electric and Siemens equipment is on the list too.
US agencies have expanded guidance on detecting malicious code changes in PLCs after observing attacks targeting Rockwell Automation, Schneider Electric, Siemens, and other internet-exposed industrial controllers.
Attackers access exposed devices via OT ports (44818, 2222, 102, 502) and modems over SSH (port 22), then exfiltrate PLC project files using vendor tools such as Studio 5000, EcoStruxure Control Expert, and TIA Portal. They modify or delete project logic, including Add-On Instructions (AOIs), manipulate HMI and SCADA displays, and disable shutdown and alarm functions, allowing industrial systems to enter unsafe states without alerting operators.
Organizations should follow vendor security best practices, remove PLCs from direct internet access using secure gateways and firewalls, and monitor logs for indicators of compromise and suspicious traffic on OT ports such as 44818, 2222, 102, and 502. Rockwell users should set controllers to Run mode, while suspected victims should contact vendors and federal agencies.
The agencies say potentially any internet-exposed industrial control system could be a target. Here’s the part that should make plant operators lose some sleep. In one case, the hackers didn’t just peek at a system. They rewrote the controller’s programming logic to disable the processes meant to trigger shutdowns and alarms during dangerous conditions.
“At one U.S. victim, the FBI observed the APT actors download a malicious project file to a targeted PLC using configuration software. Analysis indicated the project file retained ladder logic for downstream function but added logic that overrode specific instruction sets responsible for maintaining safe operating parameters in the victim’s environment.
“Since at least March 2026, the authoring agencies identified (through engagements with victim organizations) an Iranian-affiliated APT group disrupted the function of PLCs.” states the advisory. “Organizations across several U.S. critical infrastructure sectors (including Government Services and Facilities, WWS, and Energy Sectors) deployed these PLCs within a wide variety of industrial automation processes. Some of the victims experienced operational disruption and financial loss.”
Systems could then drift into unsafe territory with nobody watching the warning lights, because the warning lights had been switched off from the inside.
“After the actors extracted device project files, the FBI and CISA identified the modification and deletion of project file logic, to include Add-On Instructions (AOIs) and data manipulation on HMI and SCADA displays [T1565].” continues the advisory.” Additionally, the changes disabled critical shutdown and alarm logic, allowing systems to enter unsafe conditions without notifying operators of the anomalies.”
The advisory ties the activity to the ongoing conflict between Iran and the US and Israel, framing it as an effort to cause disruption inside the United States. It fits a pattern going back to February, when the war started and Iranian-linked hacking picked up sharply across the region.
Not all of it looks like this. Some of it has been standard espionage and embarrassment campaigns, like the leak of FBI Director Kash Patel’s personal email account. Some of it has been genuinely destructive. The Iranian group known as Handala remotely wiped tens of thousands of employee devices at medical device maker Stryker, and separately claimed a breach at California’s Cal Water, saying it could disrupt the water supply. Cal Water pushed back, saying it found no sign anyone had touched its operational networks.
That’s the pattern worth watching: espionage on one track, disruption on another, and now a wider set of manufacturers exposed on the operational technology side. If your PLC talks to the internet, it’s not a bystander anymore.
Nobody wants their water plant’s alarm system to be the one thing an adversary quietly switches off. Time to check who can actually reach those controllers from outside.
Follow me on Twitter: @securityaffairs and Facebook and Mastodon
(SecurityAffairs – hacking, Iran-Linked Actors)
